1. Field of the Invention
The invention relates to a live vaccine against mumps which is adapted to human cells, and to a process for the preparation thereof from virulent mumps viruses obtained from patients suffering from an acute attack of mumps.
2. Description of the Background
Mumps or epidemic parotitis is a very widely disseminated infectious disease which in many cases, hardly causes any symptoms other than swelling of the parotid glands. The disease usually has a benign course in childhood.
After puberty the incidence of complications is sharply increased. For example, orchitis (in men) and ovaritis (in women) which may result in atrophy of the respective organs, sometimes to the extent of causing sterility, are observed. Other complications of this viral infection may affect the central nervous system and cause encephalitis, encephalomyelitis, neuritis and meningitis.
The highest incidence of the disease occurs with school age children. The infection rate is highest at this age. An incubation period of 18 to 21 days is followed by the acute febrile phase. The infectivity starts 2 days before the swelling of the glands and lasts until the swelling subsides. In the aftermath, life-long immunity is conferred on those who have recovered from the disease.
In view of the possible complications brought about by mumps attacks, especially in adults, the availability of an optimally tolerated live mumps vaccine capable of eliciting a high antibody titer is highly desirable. Where possible, vaccination is to be carried out in the first to the third year of life.
A process for culturing viruses which provide a mumps live vaccine is described in Swiss Patent Specification 475,355. This process comprises subjecting virulent mumps viruses to several passages in chicken embryo tissue culture until it is appropriately attenuated.
In principle, this process has the disadvantage that in a live vaccine prepared in this manner, the viruses have been adapted to chicken embryo tissue culture cells and still contain residues of materials from these cells. It is known that foreign proteins in the inoculated liquid may cause undesired hypersensitivity reactions in a patient. Moreover, the vaccine produced in chicken embryo tissue cultures contain undesired antibiotics such as, e.g., neomycin, which are required to prevent bacterial contamination.
Therefore, a need continues to exist for a mumps vaccine and a method of preparing a mumps vaccine containing live attenuated mumps viruses which is free from non-human proteins and antibiotics to avoid the side effects of the known vaccines.